Several luminescent materials, in particular Quantum Dots, need to be protected against moisture and oxygen because, when they are in contact with oxygen or water, they may react with it and become dysfunctional. Therefore, they need to be provided in air and liquid tight packages. Conventional ways to provide such air tight packages are manufacturing, for example, two halves of a transparent or translucent cell-like structure, providing the Quantum Dots in one of the halves and air-tightly gluing the second half to the first half. Often, the layer of Quantum Dots has to be thin, and, as such, a cavity of the cell-like structure is thin as well. When an excessive amount of glue is used, it might be that, within the cavity, a too large portion of the Quantum Dots is pushed away by the excessive amount of glue resulting in a Quantum Dot cell that has to be rejected. When organic glues are used, it is difficult to create a gas-tight package, because organic glues are often permeable for gasses. Instead of using organic glues, the two halves may be coupled to each other by means of glass frit bonding.
Luminescent materials absorb light according to an absorption distribution and they convert the absorbed energy towards light of another color that is emitted according to an emission distribution. In general the light of another color has a longer wavelength than the wavelength of the absorbed light. A further characteristic of luminescent materials, and more in particular Quantum Dots, is that they convert light less efficiently when they become relatively warm. It might even be that the Quantum Dots are degraded or even destroyed when the temperature of the Quantum Dots becomes too high. During use, luminescent materials becomes warm because of the Stokes Shifts, which means that not all absorbed light is converted towards light of another wavelength, but a portion of the absorbed light energy is converted towards heat. Therefore, when a solution is designed to air-tightly seal luminescent material, it should be capable of conducting heat away from the luminescent material.
Published patent application US2013/0223922 discloses a manufacturing of a cell-like structure that is gas-tight and in which, for example, Quantum Dots might be provided. The cell-like structure is manufactured by providing a glass-coated gasket or providing on the glass substrate a structure of low-melting temperature glass on a first glass substrate, subsequently providing, for example, the quantum dots on the first glass substrate in between the gasket or structure, thereafter providing a second glass substrate on top of this and finally tighten the cell-like structure by heating the glass-coated gasket or structure such that they fasten to the substrates. Although the glass of the glass-coated gasket or structure melts at a relatively low temperature, in a range from 200 to 500° C., the temperature may still be too high for Quantum Dots such that a substantial portion of the Quantum Dots becomes defective. Furthermore, the manufacturing process is relatively expensive, because it requires manufacturing several parts, which must be kept in stock, and which must be assembled. Therefore, the cell-like structures manufactured according to the process of the cited patent application are relatively expensive.